Leon lilieneeld



Reissu ed Aug. 25 1931 UNITED STATES,

LEON LILIENFELD, OF VIENNA, AUSTRIA ARTIFICIAL THREAD AND PROCESS FORMAKING SAME No Drawing. Original No. 1,683,199, dated September 4, 1928,Serial No. 156,751, filed December 23, 1926,

and in Austria June 20, 1925. Application for reissue filed August 16,1930. Serial No. 475,840.

The invention is based upon the observaiion that artifical threads, forexample artificial silk of high dry tenacity, are obtained by bringingviscose into the form of a thread and causing to act upon the formedthread one or more agents which have upon viscose the two followingeffects: I

1. A coagulating effect upon the formed but not yet coagulated thread,and

2. A dissolving or swelling up or plasticizing action upon thecoagulated thread.

Observations made under the iniscroscope indicate that the combinationof-the two ac tions described above results in a high dry tenacity,because the coagulation combined with either a plasticization of thethread or with a filling out of the interstices by the swollen ordissolved parts of the thread or both, imparts to the thread a muchhigher continuity than the coagulation by itself. In addition to this,the plasticization which takes place simultaneously with, orsubsequently to the coagulation, makes the coagulated thread capable ofbeing stretched during spinning to a degree unattainable if an agent isused which has a coagulating action only and no or very littleplasticizing effect.

According to the invention, the dissolving 3 or swelling or plasticizingaction of the setting bath must not be prolonged until the cellulosethread is attacked by the destroying or dcpolylnerizing action the bathmay have on the thread during its passage through the bath itself orduring the air passage between the bath and the collecting device.

In other words: The time during which the tread is in contact with thecoagulating liquid must be so chosen that no destruction ordepolymerization and no considerable loss in weight (calculated onthecontent of cellulose of the original viscose on the one hand and theweight'of the thread produced on the other) takes place, and the actionof the liquid must be checked before it has an injurious effect upon thethread.

I have further observed that strong mineral acids, particularly strongsulphuric acid, are specially suitable for the carrying out '.0f theinventive idea underlyingthe present process: The combination of acoagulating action on the one hand and of a plasticizing action on theother. on formed viscose.

In carrying out my invention, artificial threads or viscose silk ofhighdry tenacity, exceeding 2 grammes per denier, can be made for example bybringing the viscose into the form of a thread and causing to act uponthe formed thread sulphuric acid containing not less than about 50 percent. for example about per cent. of H 80 and preferably sulphuric acidcontaining more than 55 per cent. for example to 86 per cent. of H 30 Mydiscovery that such strong sulphuric acid can be used as coagulatingbath in the manufacture of artificial threads from viscose issurprising, it having been stated that with sulphuric acid of variousdegrees of concentration between 5% and {10% H 504, threads have beenobtained, which, regarded microscopically, appear to be covered withfine scales, while with concentrated sulphuric acid the formation of alustrous thread, band or the like is completely spoilt (see Max MiillersU. S. Patent 836,452).

It is still more surprising that I can manufacture from viscoseby meansof such strong sulphuric acid, threads which have a tensile strengththat surpasses that of any artificial thread known hitherto and in somecases approaches, in some cases equals, and in some cases even surpassesthat of natural fibres, such as cotton or real silk. For example, I

' am able to produce according to. the present process artificial silkor staple fibre that has a dry tenacity of considerably more than 2grammes and even,inore than 3 grammes per denier, for example 3'or even3.5 to 4 grammes per denier, and in some cases even more than 4. or insome cases even 5 grammes per denier or more, and a Wet tenacity of 1.5to 2.5 grammes per denier and more.

A further advantage of the artificial threads manufactured according tothe present process over ordinary viscose silk is their higherresistance to aqueousalkaliesand to soap.

I have further found that it is advantageous to the: tensile strength ofthe artificial threads, manufacturedaccording to the pres, out process,to apply additional stretch tothe threads either in the coagulating bathor between the coagulating bath and the collecting device or in bothplaces. The process yields however quite good results also when onlysuch stretch is applied as is usual in the viscose artificial silk art,particularly when spinning machines with a long air passage or highspinning speed or both are employed.

The process is carried out by bringing viscose into the form of anartificial thread and coagulating it by means of sulphuric acid.containing at least about 50, preferably about 55 per cent. of H SO forexample sulphuric acid containing 55 to 85 per cent. of monohydrate.

In most cases this can beefi'ected in such a manner that the viscose iscaused to pass through suitably formed openings into sulphuric acid,containing 55 to 98 per cent. of H SO;,, for instance acid of to 85 percent.

strength (calculated as H SOQ, or into a.

bath containing 55 to 98 per cent. for instance 65 to 85 per cent. ofsulphuric acid monohydrate. The strong sulphuric acid may be employed byitself, or, so far as is compatible with the conditions under which itis used,in admixture with a suitable quantity of one or more suitableinorganic substances, for example with another strong mineral acid, suchas hydrochloric acid, nitric acid'or phosphoric acid, or with a neutralor acid salt, such as sodium sulphate, sodium bisulphate, ammoniumsulphate, magnesium sulphate, zinc sulphate, sodium bisulphite, sodiumsulphite, sodium nitrite or boric acid. Again, so far as is compatiblewith the conditions under which it is used,to the strong sulphuric acidor its mixture with another strong acid or with one or more of theinorganic'substances mentioned above, there may be added a suitablequantity of one or more organic bodies, such as glycerol or a sugar, forexample glucose, or alcohol or a salt'of an organic base, for example,of aniline, or an organic acid, such as acetic acid or formic acid orlactic acid or oxalic acid. If a salt is added which is capable ofreacting with the strong sulphuric acid with formation of an acidsulphate, or which mutually interacts with the sulphuric acid, thestrength of the sulphuric acid should be so chosen that, after theamount required for the formation of the acid sulphate or for the mutualinteraction is used up, the coagulat- ,ing bath contains free sulphuricacid of the desired strength, but at any ratenot less than about 50,preferably about 55 parts by weight of monohydrate in 100 parts byweight of the precipitating bath.

, The process may also be carried out in such a'manner that the formedthread is first coagulated by meansof a setting bath known from theviscose artificial silk art regardless whether such bath coagulates theviscose in a form soluble or insolublein water, whereupon the thread istreated with a liquid that consists of, or contains one or more strongermineral acids, preferably strong sulphuric acid for example such as 50to 94 per cent or more strength (calculated on monohydrate). This canbedone, for example so, that the viscose is forced to pass throughsuitably formed apertures into a coagulating bath known from the viscoseartificial silk art, for instance into a solution of ammonium sulphateor sodium bisulphate or into, dilute sulphuric acid, for instance suchof 10 per cent strength, or into dilute sulphuric acid containing sodiumsulphate or sodium bisulphate, or into a liquid containing ammoniumsulphate and sulphuric acid, and that the thread, after having beenimmersed in said-bath for a longer or shorter time or distance, isintroduced into a second bath which consists of, or contains one or morestrong mineral acids, preferably strong sulphuric acid, for example suchof 50 to 85 per cent of H SO y Thestrength of the sulphuric aciddepends, ceteris paribus, partly on the time of maturing given thealkali cellulose, partly on the time of ripening given the finishedviscose and partly on the viscosity of the viscose or amount ofcellulose contained in the viscose. As a rule, to which, however, theinvention is not confined, it may be stated thatnviscoses which havematured for several days and viscoses that have been prepared fromalkali cellulose that has been allowed to mature for a relatively longtime, for example 2 to 3 days, and viscoses that are poor in celluloseor little viscous, do not withstand so strong a sulphuric acid asviscoses that have not been allowed to mature or have been allowed tomature for a short time only, (for instance, 3 to 48 hours) and viscoseswhich have been prepared from alkali cellulose that has been not allowedto mature or has been allowed to mature for a shorter time than v usual,for example3 to 36 hours, and viscoses amounting to over 40 per cent ofthe weight of the cellulose used in making the viscose. As a rule, whenusing the larger proportion of carbon bisulphidein the production of thevislcose longer ageing of the viscose is desirab e.

The strength of the sulphuric acid is further, to a certain degree,dependent on the length of immersion in the coagulating bath and thetension given the coagulated material in the acid or outside it, forexample room temperature, for example at to 0., or even below 0 0., forexample at from .1 to 10 C.

The length of the thread or filament inimersed in the strong sulphuricacid or in the bath containing it, may be varied within wide limits, forexample from 3'to (i0 centimetres and even more, for instance 1 to 2metres, depending generally on the spinning conditions, for instance onthe age of the viscose. on the temperature and concentration of thespinning bath, on the speed of spinning, on the denier of filamentsobtained.

If desired the thread may be stretched either immediately after itsformation, that is in the coagulating bath containing, or con sistin ofstrong sulphuric acid, or subsequent y, that is between the coagulatingbath and the collecting device, such as bobb n or centrifuge, or both inthe coagulating bath and between the coagulating bath and the collectingdevice.

Since, during prolonged contact with sulphuric acid of thestrengths'used in my process, cellulose is attacked and ultimatelydestroyed, it is essential to check the action of the acid on thefilament or the like formed, by washing or other means, fOl'lIlStilIlCEsubjecting the formed thread to a low tempera-- ture, and this ispreferably carried out be fore or during the deposition of the threadupon the bobbin or in the centrifugal box or similar device. Thisimmediate checking of the action of the acid is of less importance ifthe thread or the like is collected in thin layers, in which case asomewhat delayed washing s possible; such collection in thin layers,however, is not the best practice, for reasons wellknown to thoseskilled in the art.

The thread, after wahing, may be heated or steamed before or afterdrying.

A'ny suit-able viscose may be used in the present process. The processgives good results with viscoses that are prepared from alkali cellulosethat has been allowed to mature for such a time as is commonly allowedfor maturing alkali cellulose in the artificial silk art, butgenerallyspeaking more satisfactory results are obtained with viscoses in themanu facture of which alkali cellulose is used which has not beenallowed to mature at all, or has been allowed to mature for a shortertime than is usual in the artificial si k art, that is, not longer thanfor example about 36 hours for example 1 to 24 hours.

As a further rule it may be stated that such viscoses as are preparedfrom alkali cellulose that has not been matured or has been matured fora shorter time than is usual. in the artificial silk art, i. e. notlonger than about 36130 48 hours, for example 1 to 24 hours, yieldstrong threads if spun into sulphuric acid containing about 50 per cent'H SO whilst the lower limit of the concentration of the sulphuric acidfor obtaining strong threads from viscoses prepared from alkalicellulose that has been matured for a longer time than 36 to 48' hours(according to the quality of the starting cellulose and to thetemperature of maturing the alkali ce lulose) is about 55 per cent of H30 The present invention gives good results with such vi"coses also asare prepared by directly mixing the ingredients.

If desired, there may be added to the vi"- cose one or more suitablesubstances known in the viscose-silk art, for example glyccrine orglucose or odi um sulphate or sodium 511lphite or sodium bisnlphite orammonium sulphate or an alkali silicate or an alkali aluminate. orammonia. v

It will be seen from the foregoing statements that success in obtainingthreads of dry tenacity, exceeding 2 grau'imes per denier by the u"e ofsulphuric acid of about 55 per cent strength or more, depends upon manyfactors which vary with the particular strength of acid selected. It isimpossible to indicate every condition for success in every particularcase and it is to be understood that experiment cannot be avoided tofind whatare the conditions neces ary for success when'using aparticular cellulose a particular formof viscose and particular detailsof the spinning operation. I give the following examples of carrying outthe process without confining the invention to these particularexamples.

I to (h) (a) Place 100 parts of wood pulp contain= in; from 9-10 percent of moisture, or 100 parts of linters containing 78 per cent ofmoisture, inQOOO parts of 18% caustic soda solution at 15 C. and allowto steep for three hours, then press the pulp until its total weight is300 parts, or inthe case of linters 340 parts, then grind it in ashredding ma chine for 2 to 3 hours at 11 C, then without allowing thealkali cellulose to ripen for any further length of time, add 40 to 60parts of carbon bisulphide and allow to react for 8 hours at 15 to 18'C., then blow off any excess carbon bisulphide for 1045 minutes anddissolve the cellulose xanthate so obtained using so much water andcaustic soda that the final solution on analysis contains about 6.5 percent of ce lulose and 8 per cent of NaOH. Filter he viscose three timesthrough cotton wool,tw0 filtrations being carried out soon after itspreparation and the other just before spinning. Allow the Viscose to agefor 90-96 hours at 1315 C., for spinning. Force the viscose at a' rateof about 3 c. cfper minute through a platinum jet containing 24 holes,each of 0.12 mm. diameter into a bath containing 7 0 per cent ofsulphuric acid at 8 (1, giving the thread a length of immersion inthesulphuric acid for 80 cms. and then leading the thread through apassage in free air of at least 120 cms. and winding on a bobbin whichrotates at such a speed that the thread is drawn at about 30 metres perminute. The thread thus produced is made up of filaments of about '3 to4 deniers each. In the aforesaid air passage three glass rods aresituated over which the thread runs and which create an additionalsuitably high stretching or tension of the threads. The bobbin runs withits lower portion in wate: so that the sulphuric acid is quenched, orconsiderably diluted, at or about the moment at which the thread reachesthe bobbin. The threads are then washed, purified, dried, twisted andfinished as usual. They possess a good lustre and a tenacityconsiderably higher than that of ordinary artificial silk. For instance,I am able by my process to obtain threads possessing a dry tenacity ofmore than 2 grammes per denier and in some cases the dry tenacity hasbeen as large as or more than 4 grammes and even 5 grammes, while thewet tenacity is correspondingly high and may be, for in-H stance, 1.5 to2.5 grammes per denier or more.

The mode of operation is as in (a), except that the viscose is forced ata rate of about 0.9 to 1.2 c. e. per minute through the platinum jet,and that the bobbin rotates at such a speed that the thread is drawn atabout 18 metres per minute,- so that the thread obtained is mafie up offilaments of about 1.5 to 3 deniers eac (c) The mode of operation is asin (a) or (6), except that the temperature of the coagulating bath is 25C.

((Z) The mode of operation is as in (a),

except that the temperature of the coagulating bath is 25 C. and thatthe length of immersion is 20 to 30 centimetres only.

e) The mode of operation is as in (a) or (b), with the exception thatthe temperature of the coagulating bath is 40 to 45 C. and that thelength of immersion is 20 to 30 centimetres only.

The mode of operation is as in (a), or b ,with the difference that thebath contain about 55 per cent of sulphuric acid.

(g) The mode of operation is as in (a), or b) except that thetemperature of the coagulatin bath is -5 C.

(h The mode of operation is as in (a), or (b),'or (f), or (g), with theexception that the viscoseis allowed to age for 144 to 200 hours at 13to 15 C. before spinning.

The mode of operation is as in Example I (a), or (b), or (f), with thedifferencethat III (a) to (a) (a) 100 parts of a sulphite-pulp orlinters are impregnated with 900 to 2000 parts of a caustic sodasolution of 18 per cent strength at 15 to 18 C. and the mixture isallowed to stand for 3 to 24 hours, Then the mass is pressed to 300to400 parts and comminuted by hand or in a suitable apparatus, forinstance in a cooled shredder. The comminuted soda cellulose is thenkeptfor 60 to 72 hours at room temperature, whereafter 30 to 60 partsof'carbon bisulphide are added, and the mixture preferably whilestirring (for example in a closed kneading machine) or agitating (forexample in a sulphidizing drum), is kept for several (for example 4 to8) hours at 16 to 20 C. Thereafter the excess of the carbon bisulphideis removed by driving off or evacuating, and then the sulphidized massis dissolved in water or dilute caustic soda solution in such a mannerthat the viscose contains for a shorter (for example, 12 hours to twodays) or a longer (for example, four days to seven days) time, theviscose is spunas in Example I into one of the following precipitatingbaths (1) Sulphuric acid of 50 to 55 B., or

(2) Sulphuric acid of 45 to 50 B., or

(3) A solution of 13.3 parts of ammonium sulphate in 120 parts ofsulphuric acid of 50 to 55 B., to which 7 to 9.parts of sulphuric acidof 66 B., have been added, or

(4) A solution of 10 to 15 parts of glucose in 190 to 185 parts byweight of sulphuric acid of 45 to 55 B.

The temperature of the coagulating bath is kept at 0 to 16 C. forinstance at 8 0., or at 4 to 8 C. V

The length of the threads immersed in the coagulating bath in which theyare being formed may be short, for example 10 centimetres, or long, forinstance from 30 to 100 centimetres and more. They are then collected ona bobbin or in a spinning centrifuge which may be placed either close bythe pre- Immediately after, or .after it has been allowed to ripen at1618 C. v

cipitating bath or ina distance from 20 to 120 centimetres from thebath, whilst the Example 1. The threads are then further washed anddried.

The threads may be stretched in any known manner whilst they are in thecoagulating bath, or after they have been removed from the bath, thatis, between the coagulating bath and the collecting device. This may bedone, for example, either by choosing a more or less long distancebetween the bath and the collecting device, or by leading the threadsover rods or hooks arranged in the bath or between the bath and thecollecting device, r in the bath and between the bath and the collectingdevice.

The speed of spinning may be varied within wide limits.

If no additional stretch to the thread is applied during spinning, it isrecommendable to employ high speed.

Before the final washing, the threads may be treated in any known mannerwith a coagulating bath known in the viscose silk art, for example asolution of sodium bisulphate or sodium bisulphite or with dilutesulphuric acid or the like. I

. The Washed threads may, before or after drying, be heated (forexample, at l00-110 .C.) or steamed,

They may also be treated with any desulphurizing or bleaching agentknown in the viscose art. Y

(b) The mode of operation is as in (a), except that 75 or more parts ofcarbon bisulphide are used for the sulphidizing of the soda cellulose.

(c) The mode of operation is as in (a) or (b), with the difference thatthe soda cellulose is pressed to 200 parts.

Mode of operation as in Example III (a), or 111(6) or 111 with thedifference- (1) That the sulphidized mass is dissolved in water ordilute caustic soda solution so as to yield a viscose that contains 5 to8 per cent of cellulose, for instance, 6 to 7 per cent of cellulose(determined in the known manner by precipitating with acid, washing anddrying).

-- sulphate in 120 parts of sulphuric acid of 50 to 60 B. to which 7 to9 parts of sulphuric acid of 66 B. have been added, or

(4) A solution of 10 to parts of glucose in 190 to 185 parts ofsulphuric acid of 55 to 60 B. y

Mode of operation as in Example 111(tr), or 111 (b), or 111(0), or as inExample 1V,

" with the exception that the viscose is not allowed to mature at all,or to maturefor VI (a) to (e) (a) 100 parts of sulphite-pulp or lintersare impregnated with 900 to 2000 parts of a caustic soda solution of 18per cent strength at 15 to 18 (1., and the mixture allowed to stand for3 to 24 hours. Then the mass is pressed to 300 parts in the case ofsulphite pulp and to 340 parts in the case of linters and comminuted byhand or in a suitable apparatus, for instance, in a cooled shredder.Immediately or soon after (for example 1 hour) the comminution, 4:0 to60 parts of carbon bisulphide are added, and the mixture, preferablywhile stirring (for example in a closed kneading machine) or agitating(for example in a sulphidizing drum) is kept for several hours (forexample 4 to 12) at 16 to C. Thereafter the excess of the carbonbisulphide is removed by driving off or evacuating, and the sulphidize'dmass, the weight of which generally amounts to from about 330 to 400parts, is dissolved in 650 to 900 and in the case of linters even up to1050 parts ofa caustic soda solution of 6.5 to 10 per cent. strength.The viscose solution thus obtained is then filtered in a known mannerthrough cotton wool or a dense cotton fabric or through bothand freedfrom gas bubbles. Immediately after, or after it has been allowed .toripen at 1518 C. for a shorter (for example 12 hours to two days) or alonger (for example four to seven days) time, the viscose is spun as inExample 1 into one of the following precipitating baths (1) Sulphuricacid of 60 B., or

(2) Sulphuric acid of 55 B., or

(3) Sulphuric acid of 40 to B., or

(4) A solution of 13.3 parts of ammonium sulphate in 120 parts ofsulphuric acid of to B., to which 9 to 1.0 parts of sulphuric acidof 66B., have been added, or

(5) A solution of 15 parts of ammonium sulphate in'120 parts ofsulphuric acid of' 40 to 45 Bi, to which 9 to 10 parts of sul phuricacid of 66 Be. have been added.

(6) A solution of 10 to 15 parts of gluco e in 190.185 parts ofsulphuric acid of 55 to 60 B.

The temperature of the coagulating bath is kept at 0 to 16 (1, forinstance at 8 C. or at 4 to 8 C. V I

The threads are spun and treated during and after spinning in the samemanner asdescribed in the foregoing examples.

(1)) The, mode of operation is as in (a), with the difference thatacaustic soda solul'li) tion of 3 to per cent strength is used fordissolving the sulphidized alkali cellulose. Accordingly, the viscose issomewhat more viscous.

(c) The mode of operation is as in (a), or (12), except that 75 or moreparts of carbon bisulphide are used for sulphidising the alkalicellulose.

(d) The mode of operations is as in (a), or (b), or (c), with thedifference that the alkali cellulose is pressed to 200 parts.

(e) The mode of operation is as in (a), or (b), or (c), or (d), with thedifference that sulphuric acid of 62 to 64 B. at 8 C. is used ascoagulating bath, the viscose being 12 to 48 hours old and the speed ofspinning abnut45 to 60 metres a minute.

VII

The method of preparing the viscose differs from that described in VI(a), or (b), or (a), or (J), or (e) in that the soda cellulose, afterbeing pressed and comminuted and before being sulphidized, is allowedto.

V1 (0) to (e).

VIII (a) to (d) (a) 80100 parts of finely divided sulphite pulp orbleached cotton are mixed with 920- 900 parts of a caustic soda solutionof 8 to per cent strength. To this mixture 40 to 150 parts of carbonbisulphide are added and the mixture kept at room temperature for 12 to72 hours, preferably under continual or temporary stirring or kneading.The viscose solution thus obtained is filtered in a known manner throughcotton wool or a dense cotton fabric or through both and freed from gasbubbles, if any. Immediately after, or after it has been allowed toripen at 16 to 18 C. for a shorter (for example 12 hours to two days) ora longer (for example four days or seven days) time, the viscose is spunas in Example I into one of the following coagulating baths:

(1) Sulphuric acid of 55 to 60 B., or

(2) Sulphuric acid of 45 to 50 B., or

(3) A solution of 13.3 arts of ammonium sulphate in 120 parts osulphuric acid of 45 to 60 B. to which 7 to 9 parts of sulphuric acid of66 B. have been added, or v (4) A solution of 10 to parts of glucose in190 to 185 parts of sulphuric acid of 45 to 60 B..

The temperature of the coagulating bath is kept at 0 to16 0., forinstanceat 8 C. or at 4.t0 8 C.

The threads are spun and treated as in the exception that the viscose isprepared according to the method 3 in the British specification No.212,865, for example according to'the following examples of thatspecification. I (a) to e), or II (a) to (0), or III.(a) to (c),or V (a)to (e)',orV (a) to(b), or VI (a) or (c), or VII to VIII, or IX to X, orXII, or XIII.

(0) Mode of operation as in (a), or (b), with the exception that, beforeor after the addition of carbon bisulphide, a small quantity of acatalyzer is added to the mixture of the cellulosic body with thecaustic alkali solution, for example 0.2 to 1 part of a soluble chromicsalt or nickel salt or iron salt.

(d) Mode of operation as in (a), or (b), with the difference that,before or after the addition of carbon bisulphide, a small quantity of asoluble peroxide, such as 5 to 20 parts of sodium peroxide to 100 partsof parent cellulose is added.

100 parts of sulphite-pulp are placed in a cooled shredder adapted to behermetically closed, whereupon 200 parts of a caustic soda solutionof 12to 20 per cent strength are added, preferably in small portions. As soonas the mass is homogeneous, 40 to 60 parts of carbon bisulphide areadded, whereupon the X (a) and (b) (a) A viscose prepared according toany one of the formulas given above is spun ina well-known manner into:

(1) A solution of ammonium sulphate of to per cent strength, or

(2) In a bath consisting of 500 parts of sodium bisulphate, 7 6 parts ofsulphuric acid of 66 B. and 587 parts of water, which bath may be keptat room temperature or ata raised temperature, for instance C., or

(3) In a bath consisting of 990 parts of water, 180 parts of ammoniumsulphate, 15

.parts of zinc sulphate, 135 parts of glucose and 255 parts of sulphuricacid of 66 B.

The formed thread is introduced directly from one of the foregoing bathsinto one of the following baths: I

' (1) Sulphuric acid of B., or

(2) Sulphuric acid of 45 B., or (3) A solution of 13.3 parts of ammoniumsulphate in 120 parts of sulphuric acid of 50 iii.

to 55 B6. to which 9 to 10 parts of sulphuric acid of 66 B. are added.

The temperature of the second bath may be kept below room temperature,for instance at to (1., or at room temperature, or even above roomtemperature, for example at to 45 C.

The length of immersion given the thread in the second bath may beshort, for instance 20 centimetres, or long, for example to 100centimetres or more.

The threads are then collected whilst the sulphuric acid is quenched ordiluted as described above, and the threads are finally Washed, driedand treated as in Example I.

(1)) Mode of operation as in (a), with the difference that as secondbath hydrochloric acid of 40 per cent is used.

In all foregoing examples the arresting of v the action of the acid maybe also done by subjecting the thread leaving the coagulating bathconsisting of, or containing the strong acid to a low temperature, forinstance to 5 to 15 C. before washing.

Examples for producing staple fibre follow automatically from theforegoing examples.

According to the foregoing examples, it is possible to obtain artificialsilk or staple fibre which has a considerably greater dry or Wettenacity than silk spun under the same spinning conditions, but by meansof chemicals customary in the viscose silk art, for example by using aknown precipitating bath.

For. example, it is not- .diflicult to produce by the present inventionartificial silk having a dry tenacity of more than 2 grammes per denier,even more than 3 grammes per denier, for example 3 to 4 grammes perdenier and more and a Wet tenacity of 1.5 to 2.5 grammes per denier andmore.

Instead of stron" sulphuric acid there may be used in the foregoingexamples a strong halogen hydracid, such as hydrochloric acid, forexample of to per cent strength, or nitric acid, for example such ascontains 60 to 90 per cent of HNO or phosphoric acid, for example of 1.5to 1.86 specific gravity, or arsenic acid. for example such as containsfrom 60 to 90 per cent of H ASO In the foregoing examples, in thepreparation of viscose, instead of Wood-pulp, there may be used bleachedor unbleached cotton, or cellulose treated in the cold or in the heatwith dilute acids, for example hydrochloric m sulphuric acid, in shortany kind of cellulosic bodies used in, or proposed for, the manufactureof viscose.

The expression artificial thread in the description and claims isintended to include: artificial threads and filaments of any kind, forexample artificial silk, staple fibre, artificial cotton, artificialwool, artificial hair and ribbon straw of any kind. 1

The expression alkali cellulose which has been shortly matured meanseither an alkali cellulose made from standard commercial cellulose ofthe type commonly provided for viscose manufacture, which alkali cellu-'diminished temperature or the selection of a special type of cellulose.These means are well-known in theart.

' The expression strong mineral acid means in the description and in theclaims: sulphuric acid of at least per cent PLSO and the other mineralacids equivalent. in strength, i. e. hydrochloricacid of. at least 35per cent strengthfnitric'acid of at least per cent strength, phosphoricacid of at least 1.5 specific gravity and arsenic acid of at least 60per cent of H AsO The expression strong sulphuric acid or sulplmric acidcontaining at least 50 per cent of sulphuric acid monohydratemeans inthe description and claims sulphuric acid of 50 to 98 or 100 per centstrength.

The expression cellulose used in the product claims is intended 50 mean:cellulose or cellulose hydrate, .as the body regenerated from viscose isregarded by some cellulose chemists as cellulose, by others as cellulosehydrate.

The statements in the description and claims regarding percentagesrelate to percentages by Weight.

The present application is a part-continue ation of my copendingapplication, Ser. No. 113,582 filed June 3, 1926.

I claim 1. Process for manufacturing artificial threads of high drytenacity, exceedingQ grammes per denier, from viscose, which comprisescausing a viscose to pass through suitably formed openings into contactwith a liquid which contains not less than about per cent of sulphuricacid monohydrate.

2. Process for manufacturing artificial threads of high dry tenacity,exceeding 2 grammes per denier, 'from viscose, which comprises causing aviscose t'o.pass through suitably formed openings into contact with aliquid which contains not less than about 65 per cent of sulphuric acidmonohydratc.

and checking the action of the strong sulphuric acid not later than thethread arrives at the collecting device.

3. Process for manufacturing artificial threads of high dry tenacity,exceeding 2 grammes per denier, from viscose, which comprises causing aviscose to pass through suitably formed openings into a bath containingnot less than about 55 per cent of sulsuitably formed openings into abath containing not less than about 55 per cent of sulphuric acidmonohydrate, and applying additional stretch to the coagulated thread inthe course of its passage after it enters the bath and before it iswashed, and checking the action of the strong sulphuric acid not laterthan when the thread arrives at the collecting device.

5. The process of coagulating a viscose which comprises contacting itwith at least one strong mineral acid of a strength equivalent to atleast per cent sulphuric acid monohydrate. I

6. The process of coagulating a viscose which comprises contacting itwith a liquid which contains at least about 50.per cent sulphuric acidmonohydrate. 7. The process of coagulating a viscose which comprisescontacting it with a liquid which contains not less than per centsulphuric acid monohydrate.

8. The process of manufacturing artificial thread of high dry tenacitywhich comprises contacting a threadlike stream of a viscose with atleast one strong mineral acid of a strength equivalent to at least 50per cent sulphuric acid monohydrate.

9. The process of manufacturing artificial thread of high dry tenacitywhic comprises contacting a threadlike stream of a viscose with a liquidwhich contains at least about 50 per cent sulphuric acid monohydrate.

10. The process of manufacturing artificial thread of high dry tenacitywhich comprises contacting a threadlike stream of a Viscose .with aliquid which contains not less than about 55 per cent sulphuric acidmonohydrate.

11. The process of coagulating a viscose which comprises contacting itwith at least one strong mineralacid of a strength equivalent to atleast 50 per cent sulphuric acid monohydrate and checking the action oftlie acid before injurious effects upon the co- :igulated viscose occur.

12. The process 'of coagulating a viscose which comprises contacting itwith a liquid which contains at least about 50 per cent sulphuric acidmonohydrate and checking the .action of the acid before injuriouseflects upon the coagulated viscose occur.

13. The process of coagulating a viscose which comprises contacting itwith a liquid which contains not less than 55 per cent sulphuric acidmonohydrate and checking the contacting a threadlike stream of a viscose,with at least one strong mineral acid of a strength equivalent to atleast 50 per cent sulphuric acid monohydrate and checking the action ofthe acid before injurious effects upon the thread occur.

15. The process of manufacturing artificial thread of high dry tenacitywhich comprises contacting a threadlike stream of a viscose with aliquid which-contains at least about 50 per cent sulphuric acidmonohydrate E3 and checking the action of the acid before injuriouseffects upon the thread occur.

16. The process of manufacturing artificial thread of high dry tenacitywhich comprises contacting a threadlike stream of a. viscose with aliquid which contains not less than about 55 per cent sulphuric acidmonohydrate and checking the action of the acid before injurious effectsupon the thread occur.

17. The process of manufacturing artificial thread of high drytenacitywhich comprises contacting a threadlike stream of a viscose 'with aliquid which contains at least about 50 per cent sulphuric acidmonohydrate and diluting the strong acid adhering to the thread bywashing the threadbeforeit is injured by, the strong acid.

18. Theprocess for manufacturing artificial bodies from a viscose whichcomprises bringing a viscose into the form of an arti- 1c:

ficial body and contacting said 'body with at least one strong mineralacid of a strength equivalent to at least 55 per cent sulphuric acidmonohydrate.

19. The process for manufacturin prises bringing a viscose into. theform of an artificial thread and contacting it with at least one strongmineral acid of a strength equivalent to at least 50 acid monohydrate.

20. ,The process for manufacturing artificial thread of high drytenacity which comprises bringing a viscose into the form of anartificial thread and contacting it. with a 11a liquid which contains atleast about 50 per cent of sulphuric acid monohydrate.

21. The process for manufacturing artificial thread of high dry tenacitywhich comprises bringing a viscose into the form of an artificial threadand contacting it with a liquid which contains-not less than about 55per cent of sulphuric acid monohydrate. y

22. The process for manufacturing artificial thread of high dry tenacitywhich comprises bringing a viscose into the form of an artificial threadand contacting it with at least one strong mineral acid of a strengthequivalent to at least 50 per cent sulphuric acid monohydrate andchecking the action artificial thread of high dry tenacity whic compercent sulphuric '110 of the acid before injurious effects upon the threadoccur.

23. The rocess for manufacturing artificial thread of high dry tenacitywhich comprises bringing a viscose into the form of an artificial threadand contacting it with a liquid which contains at least 50 per cent ofsulphuric acid monohydrate and checking the action of the acid beforeinjurious effects upon the thread occur.

24. The process for manufacturing artifical thread of high dry tenacitywhich comprises bringing a viscose into-the form of an artificial threadand contacting it with a liquid which contains not less than about percent of sulphuric acid monohydrate, and checking the action of the acidbefore injurious effects upon the thread occur.

25. The rocess for manufacturing artificial thread of high dry tenacitywhich comprises bringing a viscose into the form of an artificial threadand contacting it with a liquid which contains at least 50per cent ofsulphuric acid monohydrate and diluting the strong acid adhering to thethread by Washing the thread before it is injured by the strong acid.-

26. As a new product, artificial thread of the type as obtained bycoagulating viscose in a bath containing a strong mineral acid of astrength equivalent to at least 50 per cent sulphuric acid monohydrate,consisting substantially of regenerated cellulose and having a drytenacity of considerably more than 2 grammes per denier.

27. As a new product, artificial thread of the type as obtained bycoagulating viscose, in a bath containing a strong mineral acid of astrength equivalent to at least 50 per cent sulphuric acid monohydrate,consist ing substantially of regenerated cellulose and having a drytenacity of more than 3 grammes per denier.

28. As a new product, artificial thread of the type as obtained bycoagulating viscose in a bath containing a strong mineral acid of astrength equivalent to at least 50 er cent sulphuric acid monohydrate,consisting substantially of regenerated cellulose and hav ing a drytenacity of more than 4 grammes p'er denier.

29. As a new product, artificial thread of .the type as obtained bycoagulating viscose in a bath containing a strong mineral acid of astrength equivalent to at least 50 per cent sulphuric acid monohydrate,consisting substantially of regenerated cellulose and having a wettenacity of more than 1.5 grammes per denier.

30. As a new product, artificial thread of the type as obtained bycoagulating viscose in a bath containing astrong mineral acid of astrength equivalent to at least 50 per cent sulphuric acid monohydrate,consisting substantially of regenerated'cellulose and having a wettenacity of more than 2 grammes per denier. I

31-. The processof coagulating a viscose which comprises contacting itwlth a liquid which contains at least per cent sulphuric acidmonohydrate.

32. The process of manufacturing artificial bodies from a viscose whichcomprises bringing a viscose into the form of an artificial body andcontacting said body with a liquid which contains at least 65 per centsulphuric acid monohydrate.

33. The improved process of making filaments of regenerated cellulosesilk and the like,'which comprises spinning the alkaline solutioncontaining a dissolved cellulose compound into a bath containing such ahigh concentration of an acid coagulating agent as to produce aplasticizingefi'ect on the mag ulated filaments the filaments beingunder sufiicient tension during some part of the time of contact withsuch agent, to cause a substantial elongation of the filaments.

34. The improved process of making filaments of regenerated cellulosesilk and the like, which comprises spinning the alkaline solutioncontaining a dissolved cellulose compound into a bath containingsulphuric acid of not substantially below 50% concentration to produce aplasticizing effect on the coagulated filaments, the filaments beingunder sufiicient tension during some partof the time of contact withsuch bath, to cause a. substantial elongation of the filaments.

35. The improved process of making artificial regenerated cellulosefilaments of high tensile strength, which comprises introducing finestreams of viscose into a setting bath. which contains suchahighconcentration of acid coagulating-agent, that it will have aplasticizing effect upon the coagulated filaments. the spinning beingconducted at high speed and the filaments being under suficient tensionwhile in contact with such bath to cause siibstantiahelongation of theartificial filaments during such treatment.

36. The improved process of making artificial filaments of high tensilestrength, which comprises, introducing fine streams of viscose into asetting bath, whichcontains such a high concentration of coagulatingagent, that it will have a plasticizing effect upon the coagulatedfilaments.

37 As a new product. artificial thread consisting substantiall ofregenerated cellulose and having a ry tenacity of considerably more than2 grams per denier. y

38. As a new product, artificial thread consisting substantially ofregenerated cellulose and having a dry tenacity of more than 3 grams perdenier. I

39. As a new product, artificial thread consisting substantially ofcellulose regenerated I from viscose, and having a dry tenacity of morethan 4 grams per denier.

40. As a new product, artificial thread consisting substantially ofcellulose regenerated from viscose and having a wet tenacity of morethan 1.5 grams per denier.

5 41. As a new product, artificial thread consisting substantially ofregenerated cellulose and having a wet tenacity of more than 2 grams perdenier.

, 42. As a new product, artificial thread 10 consisting substantially'of cellulose regenererated from viscose, and having. a dry te nacity ofnot substantially below 5 grams per denier. I

. 43. As a new product, artificial thread consisting substantially ofcellulose regenerated from viscose and having a wet tenacity of notsubstantially below 2.5 grams per denier,

and havinga silky luster.

44; As a new product, artificial thread consisting substantially ofregenerated cellulose, having a 'dry tenacity not below 2 grams r denierand a wet tenacity not substantia y below 1.5 rams r denier.

I L ON ILIENFELD.

